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Hill–Robertson Effect
In population genetics, the Hill–Robertson effect, or Hill–Robertson interference, is a phenomenon first identified by Bill Hill and Alan Robertson in 1966. It provides an explanation as to why there may be an evolutionary advantage to genetic recombination. Explanation In a population of finite but effective size which is subject to natural selection, varying extents of linkage disequilibria (LD) will occur. These can be caused by genetic drift or by mutation, and they will tend to slow down the process of evolution by natural selection. This is most easily seen by considering the case of disequilibria caused by mutation: Consider a population of individuals whose genome has only two genes, ''a'' and ''b''. If an advantageous mutant (''A'') of gene ''a'' arises in a given individual, that individual's genes will through natural selection become more frequent in the population over time. However, if a separate advantageous mutant (''B'') of gene ''b'' arises before ''A'' ha ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Population Genetics
Population genetics is a subfield of genetics that deals with genetic differences within and between populations, and is a part of evolutionary biology. Studies in this branch of biology examine such phenomena as adaptation, speciation, and population structure. Population genetics was a vital ingredient in the emergence of the modern evolutionary synthesis. Its primary founders were Sewall Wright, J. B. S. Haldane and Ronald Fisher, who also laid the foundations for the related discipline of quantitative genetics. Traditionally a highly mathematical discipline, modern population genetics encompasses theoretical, laboratory, and field work. Population genetic models are used both for statistical inference from DNA sequence data and for proof/disproof of concept. What sets population genetics apart from newer, more phenotypic approaches to modelling evolution, such as evolutionary game theory and adaptive dynamics, is its emphasis on such genetic phenomena as dominance, epi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Genome
In the fields of molecular biology and genetics, a genome is all the genetic information of an organism. It consists of nucleotide sequences of DNA (or RNA in RNA viruses). The nuclear genome includes protein-coding genes and non-coding genes, other functional regions of the genome such as regulatory sequences (see non-coding DNA), and often a substantial fraction of 'junk' DNA with no evident function. Almost all eukaryotes have mitochondria and a small mitochondrial genome. Algae and plants also contain chloroplasts with a chloroplast genome. The study of the genome is called genomics. The genomes of many organisms have been sequenced and various regions have been annotated. The International Human Genome Project reported the sequence of the genome for ''Homo sapiens'' in 200The Human Genome Project although the initial "finished" sequence was missing 8% of the genome consisting mostly of repetitive sequences. With advancements in technology that could handle sequenci ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Genetics In The United Kingdom
Genetics is the study of genes, genetic variation, and heredity in organisms.Hartl D, Jones E (2005) It is an important branch in biology because heredity is vital to organisms' evolution. Gregor Mendel, a Moravian Augustinian friar working in the 19th century in Brno, was the first to study genetics scientifically. Mendel studied "trait inheritance", patterns in the way traits are handed down from parents to offspring over time. He observed that organisms (pea plants) inherit traits by way of discrete "units of inheritance". This term, still used today, is a somewhat ambiguous definition of what is referred to as a gene. Trait inheritance and molecular inheritance mechanisms of genes are still primary principles of genetics in the 21st century, but modern genetics has expanded to study the function and behavior of genes. Gene structure and function, variation, and distribution are studied within the context of the cell, the organism (e.g. dominance), and within the context ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Genetic Hitchhiking
Genetic may refer to: *Genetics, in biology, the science of genes, heredity, and the variation of organisms **Genetic, used as an adjective, refers to genes ***Genetic disorder, any disorder caused by a genetic mutation, whether inherited or de novo ***Genetic mutation, a change in a gene ****Heredity, genes and their mutations being passed from parents to offspring **Genetic recombination, refers to the recombining of alleles resulting in a new molecule of DNA * Genetic relationship (linguistics), in linguistics, a relationship between two languages with a common ancestor language *Genetic algorithm In computer science and operations research, a genetic algorithm (GA) is a metaheuristic inspired by the process of natural selection that belongs to the larger class of evolutionary algorithms (EA). Genetic algorithms are commonly used to gene ..., in computer science, a kind of search technique modeled on evolutionary biology See also * Genetic memory (other) {{disa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Clonal Interference
Clonal interference is a phenomenon in evolutionary biology, related to the population genetics of organisms with significant linkage disequilibrium, especially Asexual reproduction, asexually reproducing organisms. The idea of clonal interference was introduced by American geneticist Hermann Joseph Muller in 1932. It explains why beneficial mutations can take a long time to get fixated or even disappear in asexually reproducing populations. As the name suggests, clonal interference occurs in an asexual lineage ("clone") with a beneficial mutation. This mutation would be likely to get fixed if it occurred alone, but it may fail to be fixed, or even be lost, if another beneficial-mutation lineage arises in the same population; the multiple clones interfere with each other. Mechanism of clonal interference Whenever a beneficial mutation arises in a population, for example mutation A, the carrier of the mutation obtains a higher fitness compared to members of the population without ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Vicar Of Bray (scientific Hypothesis)
The "Vicar of Bray" hypothesis (or Fisher-Muller Model) attempts to explain why sexual reproduction might have advantages over asexual reproduction. Reproduction is the process by which organisms give rise to offspring. Asexual reproduction involves a single parent and results in offspring that are genetically identical to each other and to the parent. In contrast to asexual reproduction, sexual reproduction involves two parents. Both the parents produce gametes through meiosis, a special type of cell division that reduces the chromosome number by half. During an early stage of meiosis, before the chromosomes are separated in the two daughter cells, the chromosomes undergo genetic recombination. This allows them to exchange some of their genetic information. Therefore, the gametes from a single organism are all genetically different from each other. The process in which the two gametes from the two parents unite is called fertilization. Half of the genetic information from both pa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Joe Felsenstein
Joseph "Joe" Felsenstein (born May 9, 1942) is a Professor Emeritus in the Departments of Genome Sciences and Biology at the University of Washington in Seattle. He is best known for his work on phylogenetic inference, and is the author of ''Inferring Phylogenies'', and principal author and distributor of the package of phylogenetic inference programs called PHYLIP. Closely related to his work on phylogenetic inference is his introduction of methods for making statistically independent comparisons using phylogenies. Education Felsenstein did his undergraduate work at the University of Wisconsin–Madison where he did undergraduate research under James F. Crow. He then did doctoral work under Richard Lewontin in the 1960s, when he was at the University of Chicago, and did a postdoc at the Institute of Animal Genetics in Edinburgh prior to becoming faculty at the University of Washington. Research In addition to his work in phylogenetics, Felsenstein is also noted for his work in th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Epistasis
Epistasis is a phenomenon in genetics in which the effect of a gene mutation is dependent on the presence or absence of mutations in one or more other genes, respectively termed modifier genes. In other words, the effect of the mutation is dependent on the genetic background in which it appears. Epistatic mutations therefore have different effects on their own than when they occur together. Originally, the term ''epistasis'' specifically meant that the effect of a gene variant is masked by that of a different gene. The concept of ''epistasis'' originated in genetics in 1907 but is now used in biochemistry, computational biology and evolutionary biology. The phenomenon arises due to interactions, either between genes (such as mutations also being needed in regulators of gene expression) or within them (multiple mutations being needed before the gene loses function), leading to non-linear effects. Epistasis has a great influence on the shape of evolutionary landscapes, which l ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Evolution
Evolution is change in the heritable characteristics of biological populations over successive generations. These characteristics are the expressions of genes, which are passed on from parent to offspring during reproduction. Variation tends to exist within any given population as a result of genetic mutation and recombination. Evolution occurs when evolutionary processes such as natural selection (including sexual selection) and genetic drift act on this variation, resulting in certain characteristics becoming more common or more rare within a population. The evolutionary pressures that determine whether a characteristic is common or rare within a population constantly change, resulting in a change in heritable characteristics arising over successive generations. It is this process of evolution that has given rise to biodiversity at every level of biological organisation, including the levels of species, individual organisms, and molecules. The theory of evolution by ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
William G
William is a male given name of Germanic origin.Hanks, Hardcastle and Hodges, ''Oxford Dictionary of First Names'', Oxford University Press, 2nd edition, , p. 276. It became very popular in the English language after the Norman conquest of England in 1066,All Things William"Meaning & Origin of the Name"/ref> and remained so throughout the Middle Ages and into the modern era. It is sometimes abbreviated "Wm." Shortened familiar versions in English include Will, Wills, Willy, Willie, Bill, and Billy. A common Irish form is Liam. Scottish diminutives include Wull, Willie or Wullie (as in Oor Wullie or the play ''Douglas''). Female forms are Willa, Willemina, Wilma and Wilhelmina. Etymology William is related to the given name ''Wilhelm'' (cf. Proto-Germanic ᚹᛁᛚᛃᚨᚺᛖᛚᛗᚨᛉ, ''*Wiljahelmaz'' > German ''Wilhelm'' and Old Norse ᚢᛁᛚᛋᛅᚼᛅᛚᛘᛅᛋ, ''Vilhjálmr''). By regular sound changes, the native, inherited English form of the name shoul ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mutation
In biology, a mutation is an alteration in the nucleic acid sequence of the genome of an organism, virus, or extrachromosomal DNA. Viral genomes contain either DNA or RNA. Mutations result from errors during DNA or viral replication, mitosis, or meiosis or other types of damage to DNA (such as pyrimidine dimers caused by exposure to ultraviolet radiation), which then may undergo error-prone repair (especially microhomology-mediated end joining), cause an error during other forms of repair, or cause an error during replication (translesion synthesis). Mutations may also result from insertion or deletion of segments of DNA due to mobile genetic elements. Mutations may or may not produce detectable changes in the observable characteristics (phenotype) of an organism. Mutations play a part in both normal and abnormal biological processes including: evolution, cancer, and the development of the immune system, including junctional diversity. Mutation is the ultimate source o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Genetic Drift
Genetic drift, also known as allelic drift or the Wright effect, is the change in the frequency of an existing gene variant (allele) in a population due to random chance. Genetic drift may cause gene variants to disappear completely and thereby reduce genetic variation. It can also cause initially rare alleles to become much more frequent and even fixed. When few copies of an allele exist, the effect of genetic drift is more notable, and when many copies exist, the effect is less notable. In the middle of the 20th century, vigorous debates occurred over the relative importance of natural selection versus neutral processes, including genetic drift. Ronald Fisher, who explained natural selection using Mendelian genetics, held the view that genetic drift plays at most a minor role in evolution, and this remained the dominant view for several decades. In 1968, population geneticist Motoo Kimura rekindled the debate with his neutral theory of molecular evolution, which claims that ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
